This invention pertains to apparatus for medical ventilation and, more particularly, to apparatus for controlling the inspiratory and expiratory flow and pressure of gases within a medical ventilator.
Medical ventilators, particularly anesthesia ventilators, generally offer only limited ventilatory modes of operation to the treating physician or anesthesiologist. These ventilators often comprise a flow-control valve for controlling inspiratory flow and adjustable mechanical means, if any, for controlling expiratory flow. Such mechanical means, however, are difficult to monitor and provide little flexibility. Medical ventilators offering more comprehensive ventilatory options generally are not available in anesthesia ventilators and, moreover, require complicated pneumatic hardware. This requirement increases the expense of manufacturing and requires independent control of several pneumatic valves and circuits.